This paper represents the adsorption kinetics of NO2 on single-walled carbon nanotube (SWCNT) gas sensor. The gas sensor is exposed to different concentrations of NO2 (0.5-10 ppm) for gas sensing study. To study the adsorption kinetics of analyte over SWCNT surface, an adsorption model is developed using site balance equation and mass action law. In this model, we consider the availability of reversible and irreversible adsorption sites, where analyte is adsorbed simultaneously with different rates. This model explains the response curves reasonably well and it is further used to extract the irreversible and reversible rate of reaction for different NO2 concentration exposed to gas sensor. The irreversible and reversible rate of reaction for SWCNT lies in the range 1.51 x 10(-5) to 3.17 x 10(-5) ppm(-1) s(-1) and 1.68 x 10(-2) to 9.8 x 10(-4) ppm(-1) s(-1) for different gas concentration exposed. The activation energy of reversible site lies in the range 0.6-0.8 eV, which lies within the reported range. (C) 2016 Elsevier B.V. All rights reserved.